Heat exchangers used in automotive air conditioning systems, such as evaporators or condensers, must be removably connected to refrigerant carrying lines in the system, which are under high pressure. It is important that the seal be fluid tight, and it is advantageous that the connection be simple and reliable to make and break.
A typical connector currently in use is shown in FIG. 1, and indicated generally at (10). Connector (10) is used to connect both the inlet and outlet of an evaporator to a compressor suction line (12) and a condenser liquid line (14), in one step. The ends of the lines (12) and (14) are upset or shouldered at (16) and (18) to create an axial stop surface, and are received with radial clearance through two cylindrical sealing sockets (20) and (22) bored into the face of a connector block (24). Before the lines (12) and (14) are inserted, a pair of O-rings (26) and (28) are stretched over the ends of the lines (12) and (14) and against the stop shoulders (16) and (18). Finally, a clamping plate (30) is attached to block (24), by a central bolt (32) to clamp the stop shoulders (16) and (18) in place. The abutment of plate (30) with block (24) signals the assembler that the connection is complete. However, the compression control of the O-rings (26) and (28) arises not from the axial tightening of bolt (32) or from the abutment of plate (30), but instead from the radial interference with the sealing sockets (20) and (22).
An advantage of the typical connection just described is that the shoulders (16) and (18) act as retainers to prevent the rings (26) and (28) from being blown axially out of their sockets (20) and (22) by the high pressure refrigerant. A disadvantage is that the rings (26) and (28) may become damaged or cocked as they enter the sockets (20) and (22), especially with repeated making and breaking of the connection. Furthermore, the degree of compression of the seal is dependent upon the radial gap between the upset ends of the lines (12) and (14) and their respective sockets (20) and (22). That gap cannot be held as precisely as the gap between two machined surfaces.